title: New antiferromagnetic perovskite CaCo3V4O12 prepared at high-pressure and high-temperature conditions.
abstract: A new perovskite, CaCo(2+)3V(4+)4O12, has been synthesized at high-pressure and high-temperature (HP-HT) conditions. The properties of this perovskite were examined by a range of techniques. CaCo3V4O12 was found to adopt a double-perovskite cubic lattice [a = 7.3428(6) Å] with Im3 symmetry. We have established that this new perovskite is stable at ambient conditions, and its oxidation and/or decomposition at ambient pressure begins above 500 °C. It undergoes an abrupt antiferromagnetic transition around 98 K. Electrical resistivity data suggest semimetallic conductivity in the temperature range of 1.6-370 K. We have established that the Co(2+) ions in CaCo3V4O12 are in the high-spin state with a sizable orbital moment, even though their square-planar oxygen coordination could be more suitable for the low-spin state, which is prone to Jahn-Teller distortion. Electrical resistivity curves also exhibit a distinct steplike feature around 100 K. CaCo3V4O12 is a first example of perovskite in which the sites A' are fully occupied by Co(2+) ions, and hence its synthesis opens the door to a new class of double perovskites, ACo3B4O12, that may be derived by chemical substitution of the A sublattice by lanthanides, sodium, strontium, and bismuth and by other elements and/or of the B sublattice by some other transition metals.
authors.affiliation: Institute for Solid State Chemistry, Russian Academy of Sciences , Urals Division, 91 Pervomayskaya Strasse, Yekaterinburg 620990, Russia.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Ovsyannikov
authors.forename: Yury G
authors.initials: YG
authors.lastname: Zainulin
authors.forename: Nadezda I
authors.initials: NI
authors.lastname: Kadyrova
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Tyutyunnik
authors.forename: Anna S
authors.initials: AS
authors.lastname: Semenova
authors.forename: Deepa
authors.initials: D
authors.lastname: Kasinathan
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Tsirlin
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Miyajima
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Karkin